Which of the following is a primary function of Public Key Infrastructure (PKI)?

### Why this is right - **A** is true: the lesson lists key generation, including RSA key generation, as a PKI service. - **B** is true: it describes Diffie-Hellman as helping create and securely exchange symmetric session keys. - **C** is true: hashes act as fingerprints that can be compared to detect changes. ### The concept PKI is a system of cryptographic methods and trusted services, not one encryption algorithm. It can support key generation, distribution, integrity checking, and certificates that help establish trust in public keys. These services do not guarantee that a system remains available during an attack. Availability needs separate safeguards, such as resilient systems and recoverable backups. ### The other options - **D. Making every encrypted message automatically available during a denial-of-service attack**: PKI does not guarantee availability. A denial-of-service attack targets access to systems or services. ### Terms - **PKI**: Public Key Infrastructure, a system of cryptographic keys, certificates, and supporting services. - **RSA**: Rivest-Shamir-Adleman, a public-key algorithm named in the lesson for key generation. - **Diffie-Hellman**: A key-agreement method used to establish shared key material. - **Session key**: A temporary symmetric key for one communications session. ### Remember PKI supports trust, key handling, and integrity, but it cannot guarantee service availability.